AI-generated code still requires software engineers to build, test, debug, deploy, secure, monitor, be on-call, support, handle incidents, and so on. That's very expensive. It is much cheaper to pay a small monthly fee to a SaaS company.
No, they don't.
A domain expert armed with an Excel spreadsheet and the ability to write VBA macros will be enough for most business.
A prime example of this was the Reinhart/Rogoff paper advocating austerity that was widely quoted, and then it was discovered that the spreadsheet used had errors that invalidated the conclusions:
https://en.wikipedia.org/wiki/Growth_in_a_Time_of_Debt#Metho...
Just because technology is in use and "works" doesn't mean it's always correct.
The point is not that people will be using specifically Excel, but that most business only pay for software because it is the tool that gives them the most power to automate their processes. They don't need high availablility, they don't need standards compliance, they don't extensive automated tests, they won't need cloud engineeers and SRE... all you need is some tool that can get the results your are looking for right now.
Academia already works like this. Software wrtiten for academic purposes is notoriously "bad" because it is not engineerd, but that doesn't matter because it is good enough to deliver the results that researchers need. Corporate IT will also start looking like this even at mid-sized companies.
I've been in ops for a long time and have encountered far too many "our IP addressing plan is just a spreadsheet with manual reconciliation".
I truly wonder if Excel and all it's predecessors and direct clones (Google Sheets, etc.) are holding back industry from making something truly better and more reliable.
What "industry"?
If you are talking about the software industry, then I'd say you are creating a circular reasoning. If you are talking about all the other things that we actually need to do and which only incidentally have become too reliant on software to do it, then see back my original point: people don't need "better and more reliable" software to keep running their businesses.